1. Cross Reference to Related Applications
This application is related to our pending patent application Ser. No. 06/479,275 filed on Mar. 28, 1983, and entitled Method and Apparatus for Correcting Distortions in Reproducing Systems.
2. Field of the Invention
The present invention relates generally to an improved method and apparatus for improving the color rendition in color photos, and more particularly to apparatus and techniques for generating data useful in controlling the fidelity in color prints.
3. Description of the Prior Art
The prior art most relevant to the present invention has arisen in the area of methods and devices for evaluating color photographic negatives and determining color compensation and filter combinations to optimize the reproduction fidelity of the print. Representative of this prior art is U.S. Pat. No. 3,761,183 which issued to Yuasa, et.al. on Sept. 25, 1973, and entitled Device for Measuring Color-Compensation Quantity for Color Printing. The patent is directed to a system for determining the optimal color compensating filters to be used in a photo enlarger when printing a given negative. The system uses photo detectors sensitive in the red, green and blue spectrum ranges to sense the average spectral content of a given negative. Signals from the respective photo detectors are compared to determine the color compensating quantities in the green, blue and red signals and are thus used to determine the exposure time.
U.S. Pat. No. 4,217,648 entitled Method and Apparatus for Evaluating Color Photographic Negatives Prior to Copying which issued to Thrum, et.al. on Aug. 12, 1980, is directed to a system which provides a measure of compensation for negatives exhibiting areas of dominant color. The color density in each of the primary colors in each of a plurality of unit areas of a negative is measured and compared in a computer with the respective densities in adjacent areas. The difference between the results of the measurements of two adjacent unit areas is stored only when it is below a predetermined value. The stored results indicate the presence or absence of areas of dominant color and are used to adjust the copying light accordingly.
Early developments in this same field included that in U.S. Pat. No. 3,199,402 which issued to Hunt, et.al. on Aug. 10, 1965, which disclosed a method of measuring the amount by which the color of the printing light has been altered with the necessary calibrations for such. The disclosed arrangement involved the use of photo electric cells filtered so as to reproduce the spectral sensitivity curves of the color print material being used. Output from differently filtered cells are subtracted from one another in pairs so that only differences and not absolute magnitudes are measured. Thus, color balance was evaluated independently of overall intensity providing greater control in the system.